| 摘要 |
1,068,785. Indexing. GLEASON WORKS. May 7, 1965 [June 8, 1964], No. 19386/65. Heading B3B and B3L. An index mechanism comprises a pawl 52 to engage equally spaced formations in an indexing plate 51, and reversible drive means for driving the plate in one direction only, the means enabling a fraction of a turn or several turns to be made and being co-ordinated with movement of the pawl. The mechanism is part of a gear-cutting machine having a tool cradle 2 and a work-spindle 5 as described in Specification 1,066,692. A driven shaft 7 carries a cam 8 to actuate the generating train, a cam 13 to feed the work and a cam 9 to actuate a reversing valve 11 controlling the indexing mechanism. The generating train includes ratio-of-roll change gears 26 and differential gears 31-33. The pawl 52 is axially adjustable on a bellcrank 54 to enable different plates 51 to be fitted, the pawl then being held clear by an eccentric 64. The pawl is engaged by a spring 57 and released by a piston 58. The plate 51 is rotated by a fluid-pressure motor 66 driving through a toothed belt 69 and a threaded shaft 71. When the cam 9 operates the valve 11, the pawl 52 is withdrawn, the motor 66 starts to rotate and a clutch 73, 75 is engaged by a spring 83 on release of fluid-pressure from a piston 81. The plate 51 is thus rotated at a rapid rate until a nut 86, now travelling along the screwed shaft 71, operates a valve 98 to restrict exhaust from the motor 66 to flow through a throttle 103. The nut 86 continues to move slowly until a dog thereon engages a dog on the clutch part 75 to cause the motor 66 to stall. The travel of the nut, which can be adjusted, thus determines the degree of rotation imparted to the plate 51. The pawl is then engaged with the plate, movement of the pawl enabling fluid to be supplied to disengage the clutch 73, 75. |
